Pecan tree named ‘Treadwell’

ABSTRACT

A pecan tree distinguished by the following unique combination of characteristics: high precociousness and prolificacy, consistent production (if fruit thinned), early nut maturity, large nut size that produces mammoth halves, unusual high percentage kernel, exceptional kernel color, no kernel speckling has been observed, high resistance to N scorch, black pecan aphid, pecan leaf scorch mite, and good resistance to scab fungus.

Latin name of the genus and species of the plant: Carya illinoinensis.

Variety denomination: ‘Treadwell’.

BACKGROUND OF THE INVENTION

The present invention relates to a new and distinct variety of pecantree named ‘Treadwell.’ My new tree can be used in gardens or forcommercial production of pecan nuts. This new tree was selected fromseedlings grown from controlled pollination at the University of GeorgiaHorticulture Farm in Watkinsville, Ga., in 1989. The ‘Treadwell’selection resulted from crossing ‘Wichita’ (unpatented) as the seedparent with ‘Pawnee’ (unpatented) as the pollen parent. The resultingtree was selected when growing in a cultivated area at Watkinsville, Ga.

BRIEF SUMMARY OF THE INVENTION

‘Treadwell’ is distinguished from other pecan varieties known to theinventor due to the following unique combination of characteristics:high precociousness and prolificacy, consistent production (if fruitthinned), early nut maturity, large nut size that produces mammothhalves, unusual high percentage kernel, exceptional kernel color,immunity to kernel speckling, high resistance to N scorch, black pecanaphid, pecan leaf scorch mite, and good resistance to scab fungus.

Asexual reproduction of ‘Treadwell’ by grafting, (top working) onto‘Desirable’ (unpatented) pecan trees in 2002 and 2007 at locations inLeary, Ga. and Albany, Ga., respectively, was performed in order toevaluate these trees. Asexual propagation of ‘Treadwell’ pecan trees hasalso been performed at other locations in Georgia. Asexual reproductionof ‘Treadwell’ has shown that the forgoing characteristics come true toform, are firmly fixed, and are established and transmitted throughsucceeding propagations.

Certain characteristics of this variety, such as growth and color, maychange with changing environmental conditions (e.g., light, temperature,moisture, nutrient availability, or other factors). Color descriptionsand other terminology are used in accordance with their ordinarydictionary descriptions, unless the context clearly indicates otherwise.Color designations are made with reference to The Royal HorticulturalSociety (R.H.S.) Colour Chart.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a photograph showing a fruit cluster of ‘Treadwell’ pecans.

FIG. 2 is a photograph showing the leaves of ‘Treadwell’.

FIG. 3 is a photograph showing the characteristic russet shuck of‘Treadwell’.

FIG. 4 is a photograph showing nut shape and kernel characteristics of‘Treadwell’. From left to right in FIG. 4: the top views depict thesuture side and the non-suture side of the nut; and the bottom views,from left to right, depict the ventral side of the kernel, the kernel incross-section (dorsal side up), and the dorsal side of the kernel.

FIG. 5 is a photograph showing kernel and color of ‘Cunard,’ ‘Byrd,’ and‘Treadwell’, with ‘Cunard’ (now U.S. Plant Pat. No. 24,373) being on theleft, ‘Byrd’ (U.S. Plant Pat. No. 20,867) being in the middle and‘Treadwell’ being on the right in FIG. 5.

The colors of an illustration of this type may vary with lighting andother conditions. Therefore, color characteristics of this new varietyshould be determined with reference to the observations describedherein, rather than from these illustrations alone.

DETAILED DESCRIPTION

Botanical

The following detailed description of ‘Treadwell’ is based onobservations of the original tree growing in Watkinsville, Ga. and ofasexually reproduced progeny growing in Albany, Ga. and Leary, Ga.

-   Varietal name: ‘Treadwell’.-   Parentage:    -   -   Seed parent.—‘Wichita’.        -   Pollen parent.—‘Pawnee’.-   Tree:    -   -   Overall shape.—Moderately spreading, height to width ratio            is about 1:1. Tree stature is short and about one half of            ‘Byrd’ and ‘Cunard’.        -   Vigor.—Vigorous, precocious, ‘Treadwell’ fruited the second            year after grafting (top working) onto ‘Desirable’ trees,            and has done so in subsequent years. Original tree fruited            10 years from seed.        -   Height.—Of original tree, about 11 meters.        -   Width.—Of original tree, about 11 meters.        -   Trunk.—Of original tree (measured ½ meter above ground            level) about 0.8 meters circumference.        -   Trunk bark texture.—Scaly with tree maturity.        -   Trunk bark color.—Grey (RHS 202B).        -   Patches.—Trunk has no markings.        -   Branch color.—Branch shoots in woody stage are Grey-brown            (RHS 199A) in color, with Grey-brown lenticels (RHS 199D)            that are elongated and about 1 mm long by 0.05 mm wide.        -   Internodes.—Average internode length is about 1.3 cm,            between the 3^(rd) and 4^(th) leaf on a shoot.        -   Bearing.—Consistent production of fruit if thinned.        -   Disease and insect resistance.—High resistance to N scorch.            High resistance to black pecan aphid Melanocallis            caryaefoliae (Davis). High resistance to pecan leaf scorch            mite Eotetranychus hicorire (McGregor). Good resistance, but            not immunity, to scab Fusicladosporium effusum (G. Winters)            Partridge & Morgan-Jones.-   Leaves: The mature leaf is odd pinnate compound, deciduous with    leaflets having a dark green upper surface and a lighter green lower    surface. Each mature leaf has from 13 to 17 leaflets. Leaf    architecture is mixed on the same shoot. Some leaflets droop    slightly whereas on other leaves drooping is not present, opposite    leaflets are oriented at 180° relative to the rachis (see FIG. 2).    -   -   Size of mature leaf (fourth leaf from base).—14.4 cm long,            19.2 cm wide.        -   Peduncle.—Oval in cross-section, tan in color (RHS 199B).            The length of the peduncle of the fourth leaf from the base            is about 4.3 cm. The diameter of the peduncle of the fourth            leaf from the base is about 2.7 mm.        -   Leaflet.—Size and shape: Fourth leaflet on fourth leaf from            base 9.7 cm long by 3.0 cm wide. Falcate in shape. Base            oblique. Margin serrate. Convolution of leaflets is absent            on basal leaves, but increases from basal to apical leaves            on vigorous shoots. Leaflets are non convoluted on mature            trees. Texture: Smooth. Sheen: Glossy. Petiole: Sessile.            Margin: Serrate. Tip shape: Acuminate and narrow. Leaflet            color: Upper leaf surface: Forest green (RHS 137A). Lower            leaf surface: Green (RHS 138A). Pubescence: Upper leaf            surface is not pubescent. Lower surface is pubescent. The            length, width and other measurements were obtained from            observations of a typical leaf.-   Inflorescence:    -   -   General.—The ‘Treadwell’ pecan is monoecious, anemophilous,            and protandrous.        -   Flowers.—Pistil flowers are borne on a determinate spike,            with staminate flowers borne on a determinate pendulous            catkin. Three-five individual pistillate flowers per spike,            borne alternately on terminally-positioned spikes. The            pistillate flower is symmetrical with no stamens or petals.            The pedicels are sessile. The staminate or catkin length is            84 mm and width is 6 mm. The staminate color is Green (RHS            144B) with gold pollen (RHS 3A). The involucre size, which            includes the stigma, is 11.7 mm long by 2.8 mm wide. The            flower has one pistil with an oxblood (RHS 61 A) stigma. The            flower has four bracts, which are green (RHS 144A),            lanceolate, 4.4 mm long by 0.5 mm wide and are fused at the            bases, forming a copular involucre.-   Fruit: Mature fruit is dehiscent.    -   -   Shuck.—Green (RHS 144B), russet with maturity (see FIG. 3).            The shuck sutures are slightly winged (see FIG. 1) and the            shuck surface is not indented. ‘Treadwell’ produces a low            percentage (<5%) of undersized fruit (“green pops”) in which            the kernel does not develop and the shuck fails to dehisce.        -   Fruit split during water stage.—Not observed to be a            problem.        -   Shuck decline.—Shuck dieback during kernel formation has not            been observed to be a problem.-   Nuts: Observations from a limited number of typical nuts from    several growing seasons in Watkinsville, Ga.    -   -   Size.—Large, length about 40 mm, width about 21.6 mm (width            measurement taken midway along the length of the nut and            across sutures); length to width ratio about 1.9. Nut            flatness (ratio of width across sutures to width between            sutures) is about 1.0.        -   Form.—Oblong with a blunt (obtuse) base and a round cross            section, apex shape is cuspidate to cuspidate asymmetric,            with a grooved apex.        -   Sutures.—Non-elevated.        -   Dorsal grooves.—Narrow and shallow, thereby increasing the            percentage kernel in the nut.        -   Weight.—8.7 grams per nut (non-limiting soil moisture).        -   Cluster size.—About 2.7 fruits per cluster.        -   Shell texture.—No ridges.        -   Shell thickness.—Thin, 0.73 mm.        -   Kernel color.—Good color, Greyed-orange (RHS 165B).        -   Kernel coat.—No speckling has been observed.        -   Kernel percentage of nut.—About 64 percent (non limiting            soil moisture).        -   Nut maturity.—September 24th. Later than ‘Byrd’ by about 3            days.        -   Harvestability.—Suitable for machine harvest.        -   Cracking/shelling ability.—Cracks exceptionally well,            percentage of kernels with intact halves is high. Typically,            less than five percent of chipped or broken kernels were            observed.

COMPARISONS TO OTHER VARIETIES

The form of ‘Treadwell’ trees is moderately spreading and similar toboth parents and is shorter in stature than ‘Byrd’, ‘Cunard’, ‘Morrill’(U.S. Plant Pat. No. 23,335) and most other pecan varieties. The timingof bud break of ‘Treadwell’ is similar to ‘Byrd’ and ‘Cunard’ andearlier than ‘Morrill’, ‘Stuart’ (unpatented), and many pecan varieties.Thus, ‘Treadwell’ is somewhat more susceptible to late-spring freezes inGeorgia than ‘Stuart’ and ‘Morrill’. The leaves of ‘Treadwell’ are darkgreen and similar to both parents. Leaflet orientation of ‘Treadwell’leaves is unlike ‘Huffman’ (soon to be patent pending), that is, leafarchitecture is mixed on the same shoot. Some leaflets droop slightlywhereas on other leaves drooping is not present, opposite leaflets areoriented at 180° as in the parent ‘Pawnee’. Leaflets are non convolutedin ‘Treadwell’ except on vigorous shoots. The stigmatic surface of‘Treadwell’ is oxblood (RHS 61A), similar to the oxblood color of parent‘Pawnee’ and in contrast to the green surface of parent ‘Wichita’(unpatented). In the comparison tables below, ‘Cheyenne’, ‘Elliott’ and‘Schley’ are unpatented varieties.

TABLE 1 Approximate periods of pollen shedding and stigma receptivityfor ‘Treadwell’ and selected other varieties in May.

..... = Period of stigma receptivity. ___ = Period of pollen shedding.Tables 2 and 3 below compare the characteristics of nuts from‘Treadwell’ with nuts of other pecan varieties.

TABLE 2 Comparison of nut characteristics of ‘Byrd,’ ‘Pawnee,’‘Morrill,’ ‘Cunard,’ ‘Treadwell,’ and ‘Stuart pecan varieties,Watkinsville, Georgia. Nut Nut Shell Nut Wt./nut Nuts/lb length Length/Flatness thickness Kernel Maturity Variety (g) (no.) (mm) width^(z)ratio^(y) (mm) (%) date^(x) ‘Byrd’ 7.7 bc 60 ab 42.5 b 1.87 c 1.04 b0.65 c 63.0 b 21 de ‘Pawnee’ 7.6 c 61 a 41.9 bc 1.95 b 0.96 d 0.77 b59.5 c 20 e ‘Morrill’ 8.5 b 54 bc 47.1 a 2.01 b 1.11 a 0.72 bc 66.2 a 33b ‘Cunard’ 9.4 a 48 c 47.7 a 2.13 a 1.01 c 0.73 b 61.8 bc 26 c‘Treadwell’ 7.5 c 61 a 40.1 cd 1.86 c 0.97 d 0.73 b 59.8 c 24 cd‘Stuart’ 7.5 c 61 a 38.9 d 1.69 d 1.01 c 0.90 a 47.7 d 40 a Meansfollowed by the same letter within a column are not statisticallydifferent, P ≦ 0.05. ^(z)Length to width ratio = nut length divided bywidth. Width was measured midway the length of the nut and acrosssutures. ^(y)Nut flatness ratio = ratio of nut width across sutures towidth between sutures. Measurements were made midway the length of thenut. ^(x)Date when shuck dehiscence had occurred on 50% of the fruit,from September 1.

TABLE 3 Nut characteristics of ‘Morrill,’ ‘Cunard,’ and ‘Treadwell,’Albany, Georgia. Variety Lbs./tree Nuts/lb. (no.) Kernel (%) ‘Morrill’27 a 45 a 66.2 b ‘Cunard’^(z) 32 a 40 a 60.9 a ‘Treadwell’^(z) 34 a 52 b61.3 a Means followed by the same letter within a column are notstatistically different, P ≦ 0.05. Greater nut size and percentagekernel in Albany, Georgia as compared to Watkinsville, Georgia (Table 2)believed due to better irrigation and probably higher temperatures inAlbany, Georgia. Soil water was non-limiting at Albany, but not atWatkinsville. ^(z)‘Cunard and ‘Treadwell’ were fruit thinned as needed.About 50% of the fruit was removed. ‘Morrill’ was not fruit thinned.

Pecan nuts of large size that mature relatively early command a premiumprice. The price per pound normally declines as the harvest becomeslater. Consequently, cultivars that exhibit early maturity at harvestare commercially important. The color of a kernel's seed coat (lighteris preferred), and the percentage kernel of the nut also affects theselling price of pecans. Nut maturity of ‘Treadwell’ is early, similarto ‘Byrd’ and ‘Cunard’, slightly later than ‘Pawnee’ and 21 days before‘Desirable’. ‘Desirable’ (unpatented) is believed to be the leadingcultivar now being planted in new orchards in Georgia.

As can be seen from Tables 2 and 3, the nut size of ‘Treadwell’ nuts issimilar to that of ‘Pawnee’ and ‘Byrd’ and smaller than ‘Cunard’ and‘Morrill’. However, the nut length is shorter in the case of ‘Treadwell’nuts than ‘Byrd’ nuts and the nut shape differs. As indicated by thelength to width ratio, ‘Treadwell’ nuts are less oblong than ‘Pawnee’nuts. In cross-section, ‘Treadwell’ and ‘Pawnee’ nuts are near round(flatness ratio 0.97 and 0.96, respectively) while ‘Byrd’ nuts areflatter on the suture side than the non-suture side. Referring to Table2, the shell thickness of ‘Treadwell’ is similar to ‘Pawnee’ but thickerthan ‘Byrd’. All three have unusually thin shells, which accounts, inpart, for their high percentage kernel. However, the percentage kernelof ‘Treadwell’ and ‘Cunard’ nuts is substantially lower than nuts of‘Byrd’, which has a thinner shell. The morphology of the dorsal groovesalso affects percentage kernel. ‘Morrill’ has exceptional narrow andshallow grooves resulting in a very high percentage kernel. Thepercentage kernel is a direct function of the shell thickness and thepercentage of the shell cavity filled with the kernel.

The percentage kernel of ‘Treadwell’ nuts, as can be seen from Tables 2and 3, is high, especially when soil moisture is not limiting.

Under stress, primarily fruiting stress, when ‘Pawnee’ cultivar pecantrees are grown in humid southeastern United States, the kernel seedcoats of nuts can develop conspicuous and unattractive dark spots. Thisspeckling reduces the marketability of these nuts. Speckling has notbeen observed to be a problem of ‘Treadwell’ nuts grown in Georgia.Kernel color is outstanding and superior to the other two early maturingvarieties, ‘Byrd’ and ‘Cunard’. In addition, unlike the ‘Treadwell’cultivar, during a heavy “on” nut production year for ‘Pawnee’ treesgrowing in Georgia, kernel development is relatively poor, resulting ina high percentage of the nuts being unmarketable or of reduced value.

TABLE 4 Precocity of ‘Byrd’, ‘Cunard’, ‘Treadwell’, ‘Morrill’,‘Desirable’, ‘Huffman’, and ‘Stuart’. Variety Years to initial fruiting^(z) Cunard 2 Byrd 3 Treadwell 3 Morrill 4 Desirable 4 Huffman 6Stuart >6 ^(z) Years from planting nursery trees.Table 5 below compares the fruiting characteristics of ‘Byrd,’‘Treadwell,’ ‘Huffman,’ ‘Cunard,’ and ‘Morrill’ varieties.

TABLE 5 Fruiting characteristics of ‘Byrd’ and ‘Morrill’, Albany,Georgia. Variety Years to fruiting (no.) Years until alternatebearing^(z) (no.) ‘Byrd’ 2  3 ‘Treadwell’ 2  3 ‘Huffman’ 2 >6 ‘Cunard’ 210 ‘Morrill’ 2 >9 ^(z)Years after top working mature trees to therespective cultivar.

TABLE 6 Production and nut characteristics of six year old pecan treesof ‘Byrd’, ‘Cunard’, ‘Treadwell’, and ‘Cape Fear’ (unpatented), Leary,Ga. ^(z) Yield Nuts/lb. Kernel Variety (lb/tree) (no.) (%) Byrd 13.2 a48.2 bc 63.7 a Cunard 11.8 a 41.4 a 64.3 a Treadwell 6.1 b 48.6 c 64.2 aCape Fear 2.5 c 46.8 b 56.2 b Means followed by the same letter are notstatistically different, P ≦ 0.05 n = 26. ^(z) Nut weight and kernelpercentage are higher and nuts per pound is lower than in Table 2because of better irrigation.

As apparent from Table 4, the ‘Treadwell’ variety is precocious, similarto ‘Byrd’ and second only to ‘Cunard’. Its high precocious results inearly alternate bearing (Table 5), indicating that fruit load will haveto be controlled by mechanical fruit thinning. During the third year offruiting, Treadwell is about 2.5 times more prolific than the standard‘Cape Fear’ but about 2.0 times less than ‘Byrd’ and ‘Cunard’ (Table 6).The smaller cluster size of ‘Treadwell’ than that of ‘Byrd’ and ‘Cunard’(Table 7) may account in part for its lower prolificacy but the primaryfactor is its short tree stature which can be partially compensated byincreasing the tree density per acre. ‘Treadwell's’ short stature makesit suited to high density planting which contrasts with ‘Byrd’,‘Cunard’, ‘Huffman’, and ‘Morrill’. However, the difference inprolificacy as a young tree is not a factor as a mature tree. As amature tree, prolificacy of ‘Treadwell’ is equal to the more precocious‘Cunard’ (Table 3). This occurs because both cultivars and ‘Byrd’produce more nuts as a mature tree than they can adequately mature or“fill”. This problem is universal with precocity and prolific pecancultivars. The problem is circumvented by mechanically removing orthinning the excess fruit.

TABLE 7 Fruit cluster size of ‘Byrd,’ ‘Desirable,’ ‘Morrill,’ ‘Pawnee,’‘Cunard,’ and ‘Treadwell,’ Watkinsville, Georgia. Variety Fruit/cluster(no.) ‘Byrd’ 3.1 ab ‘Desirable’ 1.5 d ‘Morrill’ 2.7 bc ‘Pawnee’ 3.1 ab‘Cunard’ 3.4 a ‘Treadwell’ 2.7 bc ‘Huffman’ 1.7 d Means followed by thesame letter are not statistically different, P ≦ 0.05.Table 8 below compares N scorch, pecan leaf scorch mite, and leaf scabsusceptibility of ‘Byrd,’ ‘Morrill,’ ‘Cunard,’ ‘Treadwell,’ and‘Desirable.’ In addition, ‘Pawnee’ has been observed to be moresusceptible to scab disease than ‘Treadwell’ when grown in Georgia.‘Wichita’, when grown in Georgia's humid climate, is highly susceptibleto scab fungus.

TABLE 8 N scorch, pecan leaf scorch mite, and leaf scab susceptibilityof ‘Byrd,’ ‘Morrill,’ ‘Cunard,’ and ‘Treadwell’. Pecan leaf LeafScab^(z) Variety N scorch^(x) scorch mite^(y) Leary, 2009 Watkinsville,2010 ‘Byrd’ 1.2 a 1.1 b 1.0 a 1.4 b ‘Morrill’ 1.5 a 1.2 b 1.3 a 2.0 b‘Cunard’ 1.1 a 2.2 c 1.3 a 1.8 b ‘Treadwell’ 1.0 a 2.7 a 1.3 a 1.6 bMeans followed by the same letter are not statistically different, P ≦0.05, n = 19. ^(x)1 = no scorch; 2 = <1% of leaves with scorch; 3 = 2 to20%; 4 = 21 to 40%; 5 = ≧ 41%. ^(y)1 = no damage; 2 = trace; 3 =multiple lesions; 4 = minor defoliation; 5 = severe defoliation. ^(z)1 =no scab lesions, 2 = occasional lesion on leaf, less than 1% of leaveswith lesions, 3 = lesions scant on 2 to 10% of leaves, 4 = lesionswidespread but no leaf distortion, 5 = lesions widespread and severeleaf distortion.Table 9 below compares the black pecan aphid resistance of ‘Byrd,’‘Morrill,’ ‘Cunard,’ ‘Huffman’, ‘Treadwell,’ and ‘Sumner.’

TABLE 9 Black pecan aphid susceptibility of ‘Byrd,’ ‘Morrill,’ ‘Cunard,’‘Huffman’ ‘Treadwell,’ and ‘Sumner,’ Leary, Georgia. Variety Black pecanaphid ^(x) ‘Byrd’ 1.9 a ‘Morrill’ 1.9 a ‘Cunard’ 1.9 a ‘Huffman’ 1.4 b‘Treadwell’ 2.1 a ‘Sumner’ 1.8 a Means followed by the same letter arenot statistically different, P ≦ 0.05. ^(x) 1 = no injury; 2 = <1% ofleaves with injury; 3 = 1-10% of leaves with injury; 4 = 11-50% ofleaves with injury; 5 = >50% of leaves with injury and partialdefoliation.

Under the humid growing conditions in Georgia, the fruit is highlysusceptible to splitting during the “water stage” (liquid endospermstage) of fruit development. Fruit split can occur following rain andaccompanying high humidity in early August in Georgia. Cultivars withpositive nut qualities have become less desirable for growing in Georgiabecause of the susceptibility to scab fungus and water splitting. Watersplit has not been observed to be a problem in ‘Treadwell’.

The ‘Treadwell’ pecan tree is therefore an improved new and distinctpecan.

I claim:
 1. A new and distinct cultivar of pecan tree, substantially asherein illustrated and described.